THE PROBLEM OF STUDYING THE PROBLEM OF THE OCEAN IN

CLIMATE

Carl WunschOcean Sciences Meeting, Orlando

March 2008

We have collectively moved from an era in which the ocean was generally regarded as nearly unchanging over decades to one in which the emphasis is on its changes.

Further shifted from delineating high frequency phenomena such as internal waves and mesoscale eddies to a focus on interannual, decadal, and longer period shifts.

Our infrastructure, and to a large degree, human society, are poorly structured to deal with multi-decadal and longer time scales (an inter-generational problem).

Example of an oceanographicstudy. Curry & McCartney, 2001.

Phenomenological time scales match or exceed the data duration

The system is very noisy and it is a truism of science that one must observe phenomena so as to clearly delineate the time scales of change and of energy. Thus multi-decadal and longer observations are required and there is no escaping the conclusion. No one would advocate the study of one-second period surface waves for only a few seconds. That is what we are doing with decadal ocean variability….

Anomaly of surface elevation, Jan 2005, ±25cm

Note the extreme spatial variability. Dynamics tells us different regions behave differently.

A year of current meter data, day-by-day from a quietpart of the ocean Sargasso Sea, 37N, 42W. How many years to get stable statistics?

Cazenave and Nerem, 2004, trends in mean sea level, 13 years, mm/y. Mean of 2.8mm/y removed. Such patterns have very serious societal consequences.

Cessi et al., 2004. Theory all implies the same problem:Example:Time in years for a North Atlantic disturbance to penetrate the world ocean (sea level). Many decades are required for its evolution and many more required to fully observe it.

A lot of physics lies between these observed motions---requiring years of study---and the Wüstian arrows (which have only direction).

Hogg & Owens, DSR, 1999

Character of the motions is position dependent.

Can one possibly understand thisWithout understanding this?

Maintaining calibration over decades is one ofthe most difficult of alltechnical problems, as aredecisions concerningtechnology replacement.

SeaOs about 2003-present

STD/CTD about 1965-present

Nansen bottles/reversing thermometers about 1860-1965

What’s next?

All the science says that observations must be:

(1) Global(2) Time continuous

(3) Of open-ended duration(4) Continuously calibrated

(5) Continuously evaluated for scientific benefit

Open ended, or operational, systems face major challenges.

(1) Sustained calibration need(2) Obsolescence of the technology is inexorable(3) Apparently higher priority, short-term budget requirements always appear.(4) Low frequency signals require great patience(5) Technicians, who are not the end-users of the data, have a hard time maintaining continuity and quality control(6) Sometimes the observations, when better understood, are no longer

regarded as high priority and one might best be discontinued---the possibility has always to be considered, but a threat to jobs and careers.

(7) Satellite systems also need to be maintained, to sample often enough (enough instruments to avoid serious aliasing ), global spatial coverage.

And that technology also evolves. Need overlaps and calibration. A complicated scientific problem in its own right.

(8) A powerful tendency (witness US and UK obsession with the North Atlantic) for scientists to focus on regions. But climate is global and omission of

major regions of observation will drastically curtail future understanding.

How do you do this?

None of this is easily consistent with academic or other time scales. It becomes a scientific-engineering-societal commitment.

Is there some way to do this, or is it beyond the capacity of human society?

Usual initial reaction is to point at the meteorological experience---a short-term set of problems leading to long-term records. Unhappily, the parallel is nither apt nor encouraging:

severe difficulties with calibration. Focus on short-term forecasting as opposed to estimation of the state. Oceanographic and general climate variations over years, generally without ongoing constituencies to sustain the observation systems.

Example of the Difficulty: The Bermuda Observatory of Henry Stommel

Tide gauge in Ferry Reach (Bermuda Biological Station)

Cable down island slope to measure temperature and bottom pressure (and plug in any new instrument as available)

Radio tracking of surface drifters

Hydrographic station (Panulirus Station →Station S)

Only the hydrographic station continues. Stommel himself abandoned the observatory idea within a few years.

Hydrography was/is subject to aliasing, bad weather, shipbreakdowns, equipment loss, quality control problems.

Cable connections were hard to maintain. On-the-bottom-of-a-slope temperatures on a large island require considerable theory to interpret.

Drifter measurements proved uninterpretable (“…false mean flows from …rectification. They repose in published obscurity.” H. Stommel, Autobiography. They didn’t know about the eddy-field.)

Tide gauge was reliable only during the lifetime of Colonel Stevens for whom it was a retirement hobby. After take-over by NOAA, record was soon interrupted.

Center of the Sargasso Sea is not representative at low frequencies of the ocean as a whole (or at least it is not obviously so).

It’s noisy. Broken up, aliased and hard to use. A crisis every 3-5 years when funding came up for renewal: “You have 10 years of data; isn’t that sufficient?”.

Global coverage by moored current meters over full water column, circa 1975-1995. Incoherent. Not cheap. Patience was required. Probably none is still in maintained.

Now operational “observatory”. Upper ocean coverage only---great missed opportunity. Is the science community truly engaged?

All the science points to the conclusion that our generation(s) will have inadequate data to “solve” the ocean-in-climate problem. Unpalatable, but how to escape the inference?

If the inference is accepted, our problem then becomes one of laying the foundation for some future generation to have adequate data. (There are parallel issues concerning climate model development and testing that I am omitting here.)

How does one sustain open-ended measurements and model scrutiny when the result will be of greatest interest to future generations? Existing infrastructure is grossly inadequate to that end. One needs a multi-decadal, century, open-ended, view.

A few organizations persist for hundreds to order 1000 years, although the true continuity of any of them is highly debatable:

Roman Catholic and Orthodox Churches, 1000+ yearsEuropean Universities, 900+ years; US universities, hundreds of yearsA handful of banks, 200 years maximum; The Hudson’s Bay Company, 200

years

The churches all had schisms, and near-collapse. The ancient universities similarly underwent interregna and were generally founded for now-suppressed religious purposes.

A strawman plan (see Baker, Schmitt, Wunsch, 2007, Oceanography) & later talk by Ray Schmitt

The scarcest asset is the right people. Need the very best scientists and engineers, but don’t need them full time.

Need decadal commitments and a mechanism for review and renewal.

Carrot: Major salary (where an issue), and research support say 50% of normal salary. Support for a student and post-doc, or laboratory funding,…. No restriction on the research pursued.

In return:

30% of time, on average, devoted to open-ended global observations and/or model assessments. Would range from lobbying governments to sustain measurements, routinely checking calibrations, testing new technologies, engaging in discussions of technology replacements, …

Would NOT be the observation-funding agency itself---that would continue to lie with governments.

Thirty to fifty, mid-career, people world-wide. Would form a kind of senate or parliament which would maintain a long-term perspective. Self-perpetuating by consensus. A 10-20 year commitment. A mechanism for reviewing individual’s activities every 10-15 years.

A globally distributed system with a managerial focus somewhere in the world.

Needs an endowment. Something under US$1billion would do it.

(Would not be the resource for funding observations.) Pocket money for some people

Harvard University endowment today is about US$35billion.

Perhaps there is another, better way. Can we get a dialogue started? Urgent: unobserved climate change is gone

forever. Not often can one identify a true inter-generational problem. This is one. Is there anything more important we can do collectively?

Thank you.